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By Lucas van Latum

A Model for Safety Swiss cheese metaphor of safety layers Image »Multiple layers with independent, often transient failure modes »For a loss to occur, all layers must fail independently and simultaneously ??Latent? failures are due to inherent system flaws ??Active? failures are due to unsafe acts

May 1, 2011

By Abhilash

Uranium is conventionally extracted using a process that employs strong acid (H2SO4) and an oxidant (MnO2) as leaching agents. This method often creates environmental problems, requires large amounts of energy, and involves a complex operational plant. It is not, however, economically attractive to extract uranium from low-grade ores by chemical leaching. Because the content of U3O8 in the Indian ore is usually below 0.1% by weight, it is necessary to develop an alternative process to enable the efficient and economic recovery of uranium. Uranium ore from the Narwapahar mines, UCIL is a type of vein deposit found in India, which accounts for ~54% in India. The ore (0.047% U3O8), though of Singhbhum area, possess exceptionally different mineralogy due to presence of some refractory minerals and richness of apatite (5%) resulting in a maximum 78% recovery through conventional processing at UCIL, with a very high consumption of sulfuric acid and pyrolusite, besides possible loss of uranium as uranium phosphate. To avoid usage of environmentally non-benign oxidants, remediation of influence of phosphates, and improve the overall process output of uranium; an alternate extraction technology using microbial isolate(s) is worthwhile exploring and the same is presented in the paper. The microbial isolate enriched with Acidithiobacillus ferrooxidans grown from source mine water was employed for bio-leaching of uranium while varying pH, pulp density (PD), particle size, etc. On varying pH at 35oC using 20%(w/v) PD and <75µm particle size, 83.5% and 78% uranium bio-recovery were observed at 1.7 and 2.0 pH in 40 days against maximum recovery of 46% and 41% metal in control experiments respectively. Whereas, it was observed that grinding of ore to finer size actually helped dissolution of uranium. Finer size particles (<45µm) gave a maximum biorecovery of 93% in 40days at 10%(w/v) PD, 1.7 pH and 35oC. The bio-recovery of uranium fell down from 93% to 82.73% and 60% on increasing the pulp density from 10% to 20% and 30% respectively for particles of <45µm size. The higher uranium dissolution during bioleaching at 1.7pH can be correlated with increase in redox potential from 433 mV to 664mV in 40 days.

Aug 1, 2010

By A. V. Lyamin, J. P. Wang, A. J. Li, Z. Qian

"For general stability analysis of rock slopes, rock mass strength and rock mass disturbance are definitely should be considered. In addition, the impact of earthquakes must be taken into account. In fact, the rock mass strength is very difficult to be assessed which causes the difficulty of analysing rock slope stability. Therefore, an empirical failure criterion, the Hoek-Brown failure criterion, has been proposed. It is one of the most widely accepted approaches to estimate rock mass strength. The rock mass disturbance is important and was found having significant influence on evaluating rock slope stability, especially for rock slope with poor quality rock mass. In the Hoek-Brown failure criterion, the disturbance factor can represent the level of the rock mass disturbance which would provide a reasonable basis for estimating rock mass strength.This research will not only discuss the slope factor of safety, but also consider the influence of the seismic force on rock slope stability assessment using pseudo-static method. In practice, only horizontal seismic coefficient is used. Various magnitudes of the disturbance factor and recommended blasting damage zone thickness are also taken into account. The blasting damage zone thickness considered ranges from 0.5 to 2.5 times of slope height. The research results have potential to be extended and then sets of comprehensive stability charts can be provided for the rock slope stability evaluations. They will be convenient tools for practising engineers. In this study, finite element upper bound and lower bound limit analysis methods are employed. Their applicability has been investigated in some previous studies. The differences between upper bound and lower bound solutions are less than ±10% which would provide reasonable and acceptable range for rock slope stability safety factor estimation."

Jan 1, 2015

By R. R. Tatiya

"The ultimate aim of a mine design is to determine the development work involved and resources required by adopting one or more specific alternatives. A part of the process is the production of mining plans/designs, an outline of the amount of work and costs involved as well as a prediction of the revenues expected. The paper aims to examine these aspects of mine design using the computer models developed. These models are capable of designing and performing economic analysis for one or more stopes for a continuous orebody. IntroductionTatiya and Allen (1987) have described ’defining stope boundaries using a computer.’ Using the stope boundaries defined or even hypothetical ones, algorithms have been prepared to design the layouts of the following stoping methods: 1. sublevel stoping (longitudinal as well as transverse);2. DTH (Down-the-hole) stoping; and3. flat back cut and fill stoping with posts and pillars.Tatiya (1989) presented this work at the 21st symposium on the application of computers and operations research in the mineral industry (APCOM). Economic analysis of a stope is the additional feature incorporated with these algorithms.The system has been tested by an economic analysis of the three stoping methods modeled for a small portion of a deposit of a copper mining complex. The deposits at this mining complex form lenses of varying shapes and sizes, having low copper content. These chalcopyrite lenses are steeply inclined with a thickness in the range of 5 m to 60 m. The strata are competent and suitable for underground mining.In different sections of the mines different sets of equipment are used to perform the basic unit operations. Some of the ore handling levels in the mines are trackless, the rest are tracked."

Jan 1, 1998

By E. O. Chisholm

Synopsis The colour changes effected in a solution of dithizone by trace amounts of copper, lead, and zinc mineralization provide a sensitive field test for these metals. The method has been used with success by the United States Geological Survey to trace zinc orebodies under residual soils. The dithizone test is used here on samples of non-residual soil overlying a gold-bearing zone in which the gold is associated with disseminated sphalerite, galena, and chalco-pyrite. A gold-bearing zone was successfully traced under overburden ranging from a few inches to five feet in depth by means of this method. The method may prove useful in guiding preliminary trenching through light overburden, by outlining the extent of copper, lead, and zinc mineralization. Introduction The dithizone test affords a rapid, simple, and delicate test for the presence of zinc in soil and water and is suitable for use under field conditions. It has recently been used with success by the United States Geological Survey to outline a zinc-rich area in the residual soil over a primary zinc deposit in Tennessee. The purpose of the present study was to ascertain whether the method could be used to trace a gold-bearing zone, containing associated zinc mineralization, under shallow, non-residual, glacial overburden. The results obtained indicate that the method can be used to guide preliminary trenching in overburden up to six feet in depth. Tests made of the water near lake-shore outcrops also indicate that favourable prospecting zones may be located from the water, within five feet of the shore. It is felt that this simple field test should find a wider use in prospecting, because, under certain conditions, it can outline favourable zones and thereby reduce the amount of blind trenching necessary. The following pages describe the type of deposit tested, the method used, the .results obtained, and the difficulties encountered by a novice in the use of this chemical procedure. The author is indebted to the officials of Nor-Penn Mines, Limited, for their co-operation while the tests were being made; to the late Richard Bouska, Kenora prospector, for helpful suggestions; and to F. W. McCamus, University of Toronto undergraduate student, who ably assisted with the work.

Jan 1, 1950

By T. Gerritsen, T. Plikas, K. Ochoa, M. Loveless, R. MacRosty, J. Reichart, R. Pula

Sidewall accretion in a smelting furnace plays an important role in furnace integrity as it provides protection to the sidewall cooling elements and thereby extends the furnace campaign life. The extreme thermal and mechanical stresses in the furnace and changes in the slag chemistry can cause the sidewall accretion to melt or break away decreasing the lining protecting the cooling elements. Thin accretion is highly undesirable as it increases the risk of exposing the cooling elements to the molten bath and in the worst case may lead to a failure. Therefore, monitoring the sidewall accretion on an operating furnace is extremely important to manage furnace integrity and to support safe furnace operation. Operators often generate estimates for sidewall accretion and refractory thickness using either copper cooler temperatures or heat load into the cooling water circuits. Multivariate statistical models, on the other hand, have the capability to consider all the process measurements simultaneously to provide a more reliable estimate. This paper describes the application of multivariate statistical models for sidewall integrity monitoring on a Flash Converting Furnace (FCF) and also discusses the online implementation of these models as the Sidewall Accretion Monitoring System. INTRODUCTION Rio Tinto’s Kennecott Utah Copper (KUC) smelter located near Salt Lake city, Utah operates a Flash Smelting Furnace (FSF) and a Flash Converting Furnace (FCF) to produce high-grade matte and blister copper respectively. Since the commissioning of smelter in 1995, several improvements were made to these furnaces to increase their efficiency and operational safety. At present, Kennecott smelter is known to be among the lowest-emission and highest energy recovery copper smelters in the world. Since the smelter start-up, Kennecott has invested in several advanced furnace monitoring practices to evaluate the integrity of the furnaces and improve their campaign life. An example is their temperature monitoring system installed for the smelting and converting furnaces, which continuously monitors the furnace sidewall temperatures and notifies the operators during temperature excursions. During an investigation on the converting furnace, it was revealed that there were frequent temperature excursions in the settler sidewall area towards the reaction shaft end of the furnace that caused significant furnace downtime. The reason for the sidewall temperature excursions was not clearly known.

Jan 1, 2019

By K. Aziz

The solutions to unsteady-state gas flow in a radial system have been reviewed in order to aid in the interpretation of drawdown data. It has been the practice to evaluate the time and rate conversion constants, directly or indirectly, by using reservoir data. This paper presents a method of determining these constants from drawdown data. A simplified approach to the de-termination for the various boundary conditions is presented. An example of a problem which illustrates the use of this theory appears in the appendix. UNSTEADY-STATE FLOW EQUATION The solution of any unsteady-state flow problem involves (1) the continuity equation, (2) the equation of state of the fluid, (3) the equation of fluid motion and (4) the boundary conditions. For the Darcy flow of a gas in the horizontal radial plane, the equation is when the viscosity, compressibility and permeability to gas flow may be assumed constant and the medium

Jan 1, 1963

By R. S. Fitzpatrick, P. Hegarty

"Gravity separation is a key technology in the recovery of a range of mineral ores including coal, tin, tungsten and tantalum. One of the problems associated with gravity concentration is that recovery is traditionally lower than for other separation techniques such as the flotation of base metals. Any improvements in recovery will, therefore, have a significant effect on the economics of operations of this type. More accurate, robust modelling of gravity separators is one means of achieving greater recoveries. Furthermore, better modelling can lead to more informed equipment selection and process design for potential economic deposits.Previous models for gravity separation equipment have typically relied on simple metal mass balances from samples of the separated products. However, with advances in technology there is a ready availability of analytical instruments for the automated quantitative determination of mineralogy. Instruments such as the Mineral Liberation Analyser and QEMSCAN make it possible to estimate particle size and density (related to mineral liberation and association) which are the primary factors in gravity separation. Models produced using quantitative mineralogy of feed streams will be potentially superior to those produced historically.This paper describes test work undertaken on a wet shaking table using a synthetic ore. The objective of this test work was to develop a model to predict the effect of changes in feed ore characteristics on shaking table performance by measuring quantitatively the mineralogy of the feed material. Particles were divided into size/density classes based on the results of QEMSCAN analyses.It was found that it was possible to use data from QEMSCAN to predict the recovery of size/density classes and to predict the effect of changes in the relative abundances of these classes on the separation. This model can potentially be used to adjust operating variables to maximise grade and recovery by monitoring the input feed. Care was needed when utilising QEMSCAN data to ensure representivity."

Jan 1, 2016

By J. Desroches, J. Burghardt, B. Lecampion, A. P. Bunger

"We present detailed comparisons between theoretical predictions and experiments for the initiation of radial hydraulic fractures transverse to a wellbore. Most of these experiments provide a measure of the time evolution of pressure, length, opening and flux entering the fracture during the test. We compare all these measurements simultaneously to our theoretical predictions, thoroughly testing hydraulic fracture initiation theory, which is shown to be predictive. These comparisons notably emphasize the difference between the initiation pressure (the wellbore pressure for which the fracture initiates) and the breakdown pressure (a misnomer which simply corresponds to the maximum pressure recorded during the test). INTRODUCTION In this paper, we will compare hydraulic fracturing laboratory experiments performed in different tight materials (PMMA, cement, shale) with the predictions from a numerical solution of the governing equations of hydraulic fracture mechanics (e.g. Geerstma & de Klerk, 1969; Detournay & Peirce, 2014). We focus on transverse radial hydraulic fractures initiating from a radial notch at the wellbore wall (see Figure 1). In particular, we will clarify the difference between the initiation pressure (the wellbore pressure at which the fracture initiates) and the breakdown pressure (a misnomer which simply corresponds to the maximum pressure recorded during a test, usually carried out at constant pump rate). This difference stems from the strong viscous effects at play during wellbore pressurization, fracture initiation and early propagation (i.e. fluid entrance in the newly created fracture). It has been observed on a number of experiments (e.g. Weijers, 1995; Zhao et al., 1996) and has a strong practical application, first because the maximum pressure is the most obvious value to report and second because that maximum value is necessary to specify injection systems."

Jan 1, 2015

By J. van Deventer

Volatile gold prices in the face of rising costs for mining and refining is causing the mines to look for new ways to reduce costs and increase recoveries. This task is complicated by the fact that the gold in hereto unexploited reserves is associated with increasingly complex ores - either preg-robbing, refractory, associated with high concentrations of copper, or all of the above. Ion exchange resins can play a significant role in this quest for improvement. Although ion exchange resins have been used in Former Soviet Union (FSU) countries for the recovery of gold for many decades, it is still not widely used in the Western World. Synthetically manufactured ion exchange resins can be tailor-made to suit the chemical and mechanical characteristics of a specific application. As such, ion exchange resins can be used in a variety of solution matrices (e.g. cyanide, thiosulphate and acid), and process designs (recovery from clear liquor after solid-liquid separation or directly from the leached pulp). In this paper, a number of applications are discussed along with a review of recent developments in ion exchange technology.

Jan 1, 2014

By Pieter van Nierop

Outline ? What is gasification? ? Gasification Technologies ? Gasification ?The early years ? Gasification ? The last decade ? The Alberta Situation ? The Importance of Gasification in Alberta ? Polygeneration ? Development ? Conclusion

May 1, 2004

By Peter A. Amelunxen, Richard LaDouceur, Courtney A. Young

"Many of the rare earth elements, the lanthanide series on the periodic table, are on the U.S. Department of Defense Strategic and Critical Materials list. In this regard, the U.S. Army Research Laboratory (ARL) has funded several projects at Montana Tech focusing on rare earth element recovery from natural resources. Current froth flotation operations utilize octyl hydroxamate for rare earth mineral extraction, however recovery is not ideal and flotation performance can be improved. Salicylhydroxamic acid (C7H7NO3) was identified as a novel collector due to similarities with n-octyl hydroxamate, notably the amine head group. Salicylhydroxamic acid is primarily used in the medical industry but due to the amine head group is ideally suited as a collector for rare earth mineral flotation.Parametric studies were performed for the flotation of rare earth minerals by modifying a wide range of variables. Mechanical variables of a 6L bench scale flotation cell, such as air inlet flow, rotor speed, and milling time for liberation were modified to elucidate energy input parameters for the desired minerals. Chemical parameters such as collector concentration and pH were varied to understand solution chemistry considerations of the salicylhydroxamic-rare earth mineral system. The study obtained a statistically significant experimental model for the flotation of rare earth minerals. A two stage compartmental model was also utilized for the determination of the first order flotation rate constants for each mineral. Optimized recovery of rare earth minerals was found to occur at near neutral pH ranges using salicylhydroxamic acid with maximum recoveries approaching ideal industrial standards although rare earth mineral grades were still not sufficient.INTRODUCTIONRare earth elements (REEs) are found in minerals that contain several REE which makes costeffective separation of the rare earths difficult. Significant scientific challenges have hindered mineral separation. The molecular similarity of rare earth elements results in minerals containing several REEs, such as bastnaesite [(Ce, La) CO3F]. This prevents efficient separation during concentration steps, for instance flotation, and has a direct impact on successive metallurgical processes. Consequently, concentration during flotation is of rare earth minerals (REM) as opposed to REE."

Jan 1, 2016

By J. K. Gowans

The Research and Design group of the Project Development Division (PDD) of Placer Dome Inc. includes metallurgical, electrical, civil and mechanical engineers. They provide metallurgical research and conceptual flowsheet development, feasibility concepts for the processing and ancillary facilities, and manage the detailed design of the facilities once approval has been given to a mining project. This paper describes how this group works, within the Project Development Division, to help develop feasibility studies with the Evaluations Group, manage detailed design, and provide support for the Construction Group. The paper briefly reviews the history and growth of the group and describes how it is evolving. The role of outside engineering firms and how they are incorporated into the division’s objectives are also discussed. The paper highlights the differences between Placer Dome’s Project Development Division and other mining groups, and why this approach fits the way Placer Dome does business.

Jan 1, 1998

By M. Li, T. H. Dubaniewicz, H. N. Dougherty

"INTRODUCTION Underground mines have the risk of accumulation of gases if not ventilated properly or during and after emergency situations when ventilation controls become damaged or stop working. Common gases that are monitored in underground coal are carbon monoxide (CO), oxygen (O2), and methane (CH4). Methane is a gas found in coal and released through mining; its explosive range is between 5% and 15%. Methane is commonly monitored on all mining equipment and with handheld gas sensors carried by most underground coal miners. Fiber optics (FO) is a popular technology applied in underground mining, particularly for its electric isolation. Many miners are familiar with FO cables hung throughout the mine, which are primarily used in the communication of voice and data (Taylor et al. 2010). Advancements in laser and fiber optics have made this technology well suited for gas sensing the harsh environment of mining applications. The work of the U.S. Bureau of Mines on the use of fiber optic monitoring of gases in mines started in 1992. Dubaniewicz et al. (1992, 1993, 1995, 1999, 2003) developed prototype gas sensors, including methane gas sensors, for research purposes. Previous research (Dubaniewicz & Chilton 1992) identified potential fiber optic gas detection cross-sensitivities associated with the index of refraction of various gases. Index of refraction effects was noted for carbon dioxide (CO2), which is produced in significant quantities by mine fires or explosions. NIOSH released a broad agency announcement (BAA) for the development and demonstration of mine safety and health technology (CDC NIOSH 2017). The objective of this announcement was to validate a sensor, specifically fiber optic, for the mine environment and test it in an actual working mine. The RSL FO sensor “OptoSniff” provided from this work is capable of hundreds of sensing points over distances of up to 20 km, has a measurement range of 0.05% to 100%, senses in an oxygen- deficient environment, and has no gas cross-sensitivity (RSL, 2014). The RSL system is totally electrically passive outside the central control unit (CCU), which can be housed in an MSHA-approved explosion-proof (XP) enclosure or in a control room outside of the permissive area. The sensor was tested in dusty and signal loss situations, showing it is tolerant of dust, has functioned at signal losses up to 90%, and was successfully tested in a mine environment for a five-month period (Walsh et al. 2014). This paper describes how the RSL FO sensor is used for testing using smoke and its contaminants for applicability in emergency situations. The testing investigates individual contaminants such as CO2, temperature, and smoke. Each test was performed separately and methane concentration, laser power, and response time data were collected."

Jan 1, 2019

By Robert E. Loftus

"The author discusses the growth in the use of ocean-going bulk carriers for the transportation of mineral commodities, and predicts future trends. The various types of tonnage carriers are described, along with the special discharging gear used, the costs involved and the duties of some of the personnel.THE FIRST CONSIDERATION in planning the ocean transportation of minerals is the type of vessel to be utilized. The modern 'Bulk Carrier' bas proved to be the most successful vehicle for the purpose. I would there-fore like to describe this fleet in some detail and at-tempt to show the impact that the bulk carrier bas bad on the movement of bulk materials."

Jan 1, 1968

By Grant J. Goddard

"The Iron Ore Company of Canada (IOC) has been in operation for over 30 years. Today, and in the future, technology and its application will play an ever more critical role in the company’s business success.The Carol Mining and Concentrating (CMC) division of IOC is energetically applying technology today to enhance performance and results, and is aggressively exploring opportunities to apply technology to support improved business results in the future.A critical area of focus is the application of technology to maintenance management performance. CMC has taken a “back to basics” approach to the fundamentals of maintenance management in 1995 and 1996. In parallel, the mine is aggressively implementing its Vision 2000 maintenance integration plan. This plan is targeted at levering the energies applied to sound maintenance management fundamentals as the company moves to a fully condition based maintenance approach.This paper discusses some of the strategies, key technologies and objectives of theVision 2000 maintenance integration plan at the mining operations of IOC."

Jan 1, 1996

By P. A. Christopher, R. H. Pinsent

"The Adanac molybdenum porphyry deposit near Atlin, in northwestern British Columbia, was discovered in 1905. It was explored extensively between 1967 and 1980.The deposit is within a complex, multi-phase, quartz monzonite stock that is a satellite of the post-accretionary, Surprise Lake Batholith. Biotite K-Ar dates range from 703 ± 2.4 Ma to 71.6 ± 2.1 Ma, indicating a Late Cretaceous age of emplacement.The deposit comprises an irregular-shaped ring or halo peripheral to a quartz monzonite porphyry dome, or ""cupola': The shape of the ring, and of a smal~ fine-grained quartz monzonite intrusion, and the presence of higher-grade mineralimtion on the eastern flank of the cupola, suggest partial control by a preminera/ structure. The deposit is truncated by a steep, northwesterly dipping, normal fault (Adera Fault) that down-dropped the northern half of the deposit by a minimum of 100 mThe deposit lacks strong zonal alteration but there are narrow envelopes of potassic alteration around some veins and local zones of intense wall-rock silicification. There is considerable retrograde alteration along postminera/ faults and fractures.Molybdenite occurs in veins and fractures, many of which are relatively flat-lying. They occur in all phases of quartz monzonite. Molybdenum is the only element of economic significance. There are vein and skarn occurrences with tungsten, tin, lead, zinc and precious metals peripheral to the deposit.In 1981, Placer Development Limited reported an ""undiluted mineable mineral reserve"" of 151 971 000 tonnes grading 0.063% Mo at a cutoff grade of 0.04% Mo and a strip ratio of 1.5:1."

Jan 1, 1995

By Matej Petružálek, Tomáš Svitek, Tomáš Lokajícek

"Migmatite from the Skalka region (Czech Republic) was chosen as the experimental rock material. It has macroscopically visible plane parallel structure (foliation). The foliation was caused mainly by biotite grains arrangement. The cylindrical samples of migmatite with subhorizontal, subvertical and oblique foliation were uniaxially loaded up to the failure. Network of 8 broad band sensors was employed for acoustic emission monitoring and ultrasonic sounding. A grid search method with anisotropic velocity model was used for AE hypocenters localization. The source types of successfully localized events were determined from the average first arrival amplitude. Structural anisotropy of tested rock material caused the anisotropy of its mechanical properties (peak strength, Young’s modulus) as well as a different way of fracturing process in dependence on the angle between axial stress and foliation plane. The combination of splitting, shearing and sliding was found to control the fracturing of sample with subhorizontal foliation. The shearing and sliding was dominant in fracturing of samples with oblique foliation. With greater dip of foliation, the role of sliding increased at the expense of shearing. Due to the favorably oriented system of microcracks already present, the shearing and splitting was at the same level during fracturing of the sample with subvertical foliation before nucleation began.INTRODUCTIONThe process of failure of low porosity rocks depends on their mechanical properties and actual stress and temperature condition. At the low pressure and low temperature, the most common way is brittle failure, which is a progressive process requiring the initiation, growth and coalescence of cracks (Lockner, 1993). Stress strain behavior of low porosity crystalline rocks, during the laboratory compression experiments, is divided into four characteristic stages: crack closure, elastic region, stable crack growth and unstable crack growth which leads to the brittle failure, Brace et al. (1966) , Bieniawski (1967), Lajtai (1974), Cai et al. (2004), Nicksiar and Martin, 2012 and 2013.The fracturing process of stressed rock begins with the crack initiation (sci), which for low porosity rocks occurs approximately at 40-50% of peak strength (sp) (Cai et al., 2004; Nicksiar and Martin, 2013). After the sci, the dilatancy begins and stable crack growth follows up to the crack damage threshold (scd), which is approximately at 80% of sp (Cai et al., 2004). After crossing the crack damage level, there is an unstable crack growth accompanied with nucleation of fault plane (sn) at 97-100% of sp. (Rao et al., 2011). The stress drop accompanied with formation of macro scale shear failure plane follows after peak stress is crossed."

Jan 1, 2015

By J. B. Hamilton

The advantages of generating and distributing electrical energy direct from the coal-fields so closely affects the mining industry that a few remarks on the unbalanced phases of coal distribution is worthy of attention. The value of coal imported into Canada from 1912 to 1921 exceeded the sum of $580,000,000. In 1922 Ontario imported 1,640,000 tons of anthracite and 9,440,000 tons of bituminous coal. I submit that the use of Saskatchewan lignite in an electrical super-power plant equipped for the carbonizing of coal, and disposal of excess gases would be the commencement of a solution of the fuel shortage in Ontario. As Saskatchewan becomes more and more populated and manufacturing increases, the amount of by-product carbonized fuel available for shipment to Ontario will increase, and its shipment to that province would decrease the trade deficit of the national balance sheet. If and when this is carried out it will mean a better and wider market for Alberta fuels in Saskatchewan and Manitoba.

Jan 1, 1924

By G. Scamans, J. Lazaro-Nebreda, Z. Fan, J. B. Patel

"Melt quality is crucial for both continuous and shape casting of light alloys and in order to improve it, removal of excessive inclusions, accumulated impurities and unwanted gases becomes necessary. To address this problem, a new multi-purpose high shear liquid metal treatment technology, based on intensive melt shearing by a rotor/stator unit, has been developed. The device ensures achieving uniform temperature and chemical composition and an efficient dispersion of gas and solid phases in the melt with minimal disturbance of melt surface, and can be used, among other things, for de-gassing and de-ironing of Al-alloy melts. Efficient degassing is achieved by dispersing each argon bubble into many small ones, which significantly increases the overall surface area of the bubbles and the time they remain in the melt capturing hydrogen before reaching the surface. This allows using much lower inert gas flow and mixing times than conventional rotary degassing. When applied to Al-alloy scrap, with accumulated iron, the high shear melt treatment speeds up the nucleation and growth of primary Fe-rich intermetallic particles, allowing a faster removal rate. Therefore it reduces processing times, increasing recycling productivity, and facilitates full metal circulation of secondary Al-alloys.INTRODUCTION Aluminium and magnesium alloys are widely considered in various industrial sectors for the purpose of weight saving (Polmear, 1995). In particular, they are used in the automotive sector, where components are mostly manufactured by high pressure die casting (HPDC) because of its simplicity and relatively low cost, but efficiency and mechanical properties are quite low compared with other processes. To date, the main focus to overcome this problem has been for improving the HPDC machinery (Dahle, 2001) but little attention has been paid to the opportunities of controlling the nature and quality of the molten metal supplied to the die. In this way, liquid metal treatment, which involves a variety of physical and/or chemical processing methods to improve melt quality prior casting, is crucial for both continuous and shape casting products."

Jan 1, 2018